1. Field of the Invention
This invention relates to pyrotechnic systems and, more particularly, to such systems in which an ignition stimulus is transmitted to a pyrotechnic device that is maintaining a pressure seal. Such systems have utility in initiators, igniters and rocket motors.
2. Description of the Prior Art
The technique of using a shock wave, generated by a detonation reaction to provide an initiation stimulus that is propagated through a hermetically sealed metal bulkhead has long been known in the prior art. Devices utilizing this technique are called through bulkhead initiators.
Such initiators accept an explosive signal or shock wave from a detonation type transfer mechanism at the upstream side of the bulkhead and convert it to a hot gas output on the downstream side of a solid barrier or bulkhead. This barrier provides a pressure seal during operation of the ordnance item. The barrier or bulkhead must have the structural integrity to withstand both the detonation sequence and the operational pressure of the ordnance device, and desirably, therefore, is made of a material such as stainless steel.
The initiation stimulus is transmitted through the sealed metal bulkhead through shock waves. The shock wave generated at the upstream side of the bulkhead by a donor charge is transferred to the metal bulkhead and is propagated therethrough to an acceptor charge. Sufficient energy is contained in the shock wave received by the acceptor charge to cause a detonation reaction. This reaction is transmitted to an output charge where it is transformed into a deflagration reaction.
Detonating type transfer mechanisms consist essentially of a train of explosive charges encased within a wrapping that forms a fuze duct. A detonation is initiated at one end of the train of explosive of the fuze duct and propagated at a high velocity, typically 24,000 feet per second (7,315 meters per second), through the train of explosive to each of the charges. In order to ensure the propagation of the detonation of the train of explosive charges, the fuze duct must contain a great quantity of explosive per unit length. This, in itself, introduces a hazard that objects positioned nearby the fuze may be damaged upon initiation of the detonation. Additionally, such a fuze must be carried and shipped as an explosive under observation of special precautionary measures prescribed for such dangerous goods.
Deflagration type transfer mechanisms have been used instead of detonation type transfer mechanisms to avoid the foregoing problems. When a deflagration type transfer mechanism is used, however, the shock wave type through bulkhead initiator must be modified to provide a "deflagration to detonation" transition on the upstream side of the bulkhead and a "detonation to deflagration" transition on the downstream side in order to be compatible with the deflagration type system. Such modification adds undesirably to the complexity and, hence, difficulty and cost of manufacturing through bulkhead initiators while still requiring the use of detonating materials and the attendant disadvantages thereof.
Thus, there is a need and a demand in the art for improvements in systems for transmitting an initiation stimulus to a pyrotechnic device which is maintaining a pressure seal. The present invention was devised to fill the technological gap that exists for systems of this type.